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Published October 28, 2011, 12:00 AM

Hortiscope: In sandy soil, water frequently but not long

Q: We planted 10 Black Hills spruce trees this spring. Most are doing very well, but three have several brown and brittle branches with no needles. My husband had the sprinkler system on for 2½ hours tonight and watered the trees three days ago for about an hour. I think they are being extremely overwatered, which is killing them.

By: Don Kinzler, INFORUM

Q: We planted 10 Black Hills spruce trees this spring. Most are doing very well, but three have several brown and brittle branches with no needles. My husband had the sprinkler system on for 2½ hours tonight and watered the trees three days ago for about an hour. I think they are being extremely overwatered, which is killing them. Because it is so dry, my husband believes it’s impossible to overwater and that they should be watered more. Please help settle this disagreement. How often and for how long should these new spruce trees be watered? We live along the Sheyenne River, so we have sandy soil. I don’t know if that matters. Thank you for your time. We really appreciate it. (West Fargo)

A: It matters a lot where you live, so thanks for letting me know. In sandy soil, watering should be more frequent but not as long because the soil drains well. As long as the soil around the roots doesn’t stay soggy, the trees should be OK with what he is doing. However, watering for more than two hours at a time is a little excessive unless the coverage is poor. Once the water percolates beyond the root zone, anything applied is wasted. You might try to convince him to water a couple of times a week for no more than 20 to 30 minutes each time.

Be sure the soil around the root zone is soaked each time. The roots should be damp or slightly dry before watering again. With the warm fall temperatures, a vigilant watering regime would not be out of place because the trees are going to be transpiring a lot.


Q: I read your answers about jade plant problems, so I’m hoping that you can help solve my problem. I have had my jade plant for more than 10 years. It has been healthy until now. Although green and plump, the leaves have started to show a silvery scale on them that I can feel when I run my fingers over them. I have tried to clean the leaves with mild, soapy water, but it hasn’t made any difference. The only thing I have changed is that I pruned the plant about three months ago because the heavy branches were touching the side of the pot and floor. The plant does seem to be growing. Your help is appreciated because I love this plant. (email reference)

A: The pruning you did should not be connected to this problem. I do not think what you describe is anything to be too concerned about. I suspect that what you are seeing is showing up on the older foliage and not the new. If it is showing up uniformly, then something else is going on. When was the last time you repotted using fresh potting soil? It could be that your soil is so solidly packed from years of watering that very little air is getting to the roots, so anaerobic conditions are developing. It would be worth checking out if it has been more than three years since your last repotting.


Q: I have pinkish Hershey kisses and sometimes goat’s head-shaped objects growing on the oak tree leaves in my area. Any ideas what these objects could be? (email reference)

A: Interesting description of galls on your oak leaves. You have nothing to worry about because these galls are a cosmetic event in most cases. Galls are caused by various insects starting early in the season as the buds are swelling and the new leaves are opening. Often a very small wasp will sting and lay an egg on a leaf, which causes this abnormal growth. Think of it as a benign tumor on the foliage. It becomes more noticeable at this time of year because the leaves are going into senescence. You can open the galls and see what you find.

These galls come and go with the changing seasons, so they might not be there next year or their numbers could be significantly reduced.


Q: I just received some woody stem grape ivy cuttings from a friend. Will they root in water or do I need to put root stimulator on the stems? Should I plant them in peat moss or compost soil? (email reference)

A: Let the cut end of the stems dry out. Propagate the stems in evenly moist soil and mist occasionally. Keep the cuttings in an area that gets filtered sunlight until you see roots forming or the cuttings are growing. This literally is a foolproof plant to grow.


Q: I have a cabernet sauvignon grapevine. There seems to be a grayish brown discoloration on the leaves, and they are somewhat powdery. I’ve pulled off the affected leaves, but the nonaffected leaves eventually get this problem as well.

Any suggestions? (email reference)

A: The fact that you are growing this variety of grape is a good indication you are not in North Dakota. Your problem sounds like powdery mildew, which is a fungal disease that is controlled with Bordeaux mixture fungicide sprays.

Because it is so late in the season, it likely isn’t worth making any application at this time. Clean up all the fallen leaves this autumn and give the vine the proper pruning next spring before the buds break open. Do the preventative applications of a fungicide to control mildew after the leaves have expanded and again as the vine continues to grow.


Q: I live in Dickinson and am wondering if porcelain vine is invasive in our area. (email reference)

A: It shouldn’t be if you are referencing one of my favorite botanical names, which is Ampelopsis brevipedunculata. It grows in Ohio, Illinois and parts of Minnesota, but nowhere in zone 3, which I think you folks in Dickinson are in.

However, if you have one with maturing berries, it can self-seed and become a weed problem. If you want to grow this fascinating vine, then go for the Elgans cultivar. It has variegated foliage and is less vigorous, so it won’t tend to take over everything it touches.


Q: About three weeks ago, I noticed some wet bark on my elm tree. After checking around for the source, I noticed several small horizontal holes drilled into the bark about 12 feet up the tree. That also is when I noticed some sort of woodpecker flitting through the branches. There was a small group of bees swarming in the area that was leaking. Today, I went to look at the tree and found the whole base of the tree swarming with bees. The bees got a little excited as I got close to the tree. The dog really got them buzzing when she approached. Something piqued the dog’s interest at the base of the tree that she had to check out. It was lucky that no one got stung. This tree seems to be wetter now than it was several weeks ago. The elm tree next to it has cracked bark that pulled away from the trunk about 4 to 5 feet up on the southwest side.

The lower branches did not have a lot of foliage. Is the elm tree compromised because of all this activity? Should it be removed or is this something that will heal itself? I would appreciate any insight you can give me. (email reference)

A: It is likely that you are seeing yellow jacket wasps doing the swarming. They are desperate for carbohydrates at this time of year. However, the sap from the tree is attractive to buzzing insects of any pedigree. The woodpecker apparently has found bark borers or some other insects in your tree that it is feeding on.

What you might have developing is wetwood, which is an internal bacterial infection working on the heartwood and causing decay. Before removing the tree, try to locate a certified arborist to inspect the trees. Go to http://goo.gl/phRT6 to locate a certified arborist in your area.


To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or email ronald.smith@ndsu.edu.

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